Conventionally in combustion equipment used in boilers, or the like, fuel supplying systems that supply fuel, such as natural gas, to a burner have included two valves in series to ensure that there is no fuel leakage when the combustion equipment is stopped. Additionally, leak detection has been performed in both valves, at the time of the pre-purge of the combustion equipment, to check whether or not these valves leak. See, for example, Japanese Unexamined Patent Application Publication 2003-130347 (“the JP '347”).
However, in the conventional valve leak detection disclosed in the JP '347, the leak detection is performed for both valves with at the time of the pre-purge of the combustion equipment, and thus there is a problem in that this causes the pre-purge to be time-consuming.
The present invention is to resolve problems such as set forth above, and an aspect thereof is to provide a valve leak detecting method for detecting a leak in a valve easily, and to provide combustion equipment, able to suppress the pre-purge loss.